The present invention relates to a charge pump booster device with transfer and recovery of the charge.
As is known, non-volatile memory devices with a single supply voltage use both negative and positive booster devices, which use charge pump circuits. The latter have the function of generating a boost voltage, which has a value greater than the supply voltage. The boost voltage is used to carry out operations of programming, reading and erasure of the memory devices.
In general, these booster devices have problems of consumption and occupation of a substantial surface area, in particular when the memory devices in which they are incorporated are used in applications which require reduced consumption, such as portable applications (digital cameras, MP3 readers, cellular telephony, smart cards), or consumer electronics applications.
Booster devices are known, which are used in low-power applications, and act at the level of the phase signals which are generated by the phase generator stage incorporated in them. In particular, these known booster devices save energy and charge the capacitors inside the booster device (boost capacitors) in two successive steps, in each of which the internal capacitors are charged to a voltage which is equivalent to half the supply voltage. In order to reduce further the energy necessary, a technique is used of sharing the charge between two parallel stages, which are controlled in push-pull form.
These known booster devices could be improved.
The technical problem on which the present invention is based consists of providing a booster device which makes it possible to save energy.
The technical problem is solved by a booster device that includes a charge pump circuit with an input terminal and an output terminal; a load capacitor with a load node that is connected to the output terminal; the charge pump circuit including a plurality of switches connected to one another in series between the input terminal and the output terminal of the charge pump circuit and defining between one another a plurality of circuit nodes; a plurality of storage capacitors with a first terminal connected to a respective circuit node and a second terminal that receives phase signals; and a circuit for switching off the pump that generates simultaneously opening signals for the switches and charge distribution/re-distribution control signals; and charge distribution/re-distribution circuit interposed between the load node and the first terminal of the storage capacitors and that is configured to receive the charge distribution/re-distribution control signals. Ideally, the charge distribution/re-distribution circuit includes a plurality of controlled switch elements interposed between the load node and the corresponding circuit node.